Such a comminuting apparatus may be used for example for comminuting wood, paper, plastic material, rubber, textiles, production residues or waste from trade and industry, but also bulky refuse, domestic refuse, paper collections and collections from waste-disposal organisations as well as hospital wastes, etc. A comminuting apparatus for such a purpose may comprise at least one drive unit having an electric motor which is operatively connected by way of a transmission device to a comminuting shaft which at its periphery has comminuting tools, the comminuting tools being co-operable with a counterpart member for comminuting the material to be processed. In that situation the material to be processed is comminuted by cutting, shearing, squeezing, tearing and/or rubbing between rotor members or in the cooperation between a rotor member and a stationary transverse member associated therewith. Such an apparatus is described for example in EP 0 419 919 B1. In addition a comminuting apparatus for such a process may comprise a plurality of rotor members with respective stationary transverse members associated therewith, between the rotor members.
Various drive concepts are known for such comminuting apparatuses. The apparatus can include for example an asynchronous motor which operates at a motor speed of about 1500 revolutions per minute at a mains frequency of 50 Hz. To set the specified speed of rotation of the comminuting shaft, the transmission of force is effected by way of a belt drive or a universally joined shaft or a clutch to the transmission in which the rotary speed is reduced to between about 50 and 200 rpm, depending on the respective demands involved. By virtue of the high transmission ratio required it is possible to use transmissions with a plurality of successive transmission stages, which reduces the level of efficiency of such apparatuses. Furthermore such apparatuses are very noisy because of the number of components of which some are moving at a high rotary speed. In addition the amount of space occupied by such a drive is large because of the different drive members which are connected together. In many cases protective covers or housings are required in order to enclose rotating shafts, clutches or belt drives between the individual units of such a drive arrangement, as may be appropriate from the safety point of view.
A further form of comminuting apparatus uses a hydraulically acting drive substantially comprising a drive motor and a suitable hydraulic pump coupled thereto and connected by way of a hydraulic circuit to a hydraulic motor which drives the comminuting shaft either by means of a step-down transmission or without a transmission. That variant is very costly and maintenance-intensive and comparatively disadvantageous in terms of efficiency. On the other hand that concept affords the advantage that the rotary speed of the comminuting shaft is adjustable over a predetermined range. The use of hydraulic drives however suffers from the disadvantage of poor efficiency and loud operating noise. Furthermore heavily loaded hydrostatic systems are maintenance-intensive by virtue of the leakages, which have been found in practice to occur in permanent operation, at the large number of connections between the individual components.